Didn't the Lil Red Express have stacks? If I recall correctly it was a gas engine (perhaps the 360cu)

Someone I work with has a 3500 (it's got the big Cummings) with 61/2" custom stacks. He regrets doing it, as they cross over in the bed (there wasn't room underneath to do the crossover there)he's caught a bale or two of hay on fire from the heat, and he has to put covers over the stacks when it rains and he's not running the truck (he calls it putting on his stack condoms). He didn't get the flappers (due to lack of a better term) and they're not angled (he says that the angled ones just put you in a cloud of diesel soot).